Alloy/Interface-Induced Activation of Metal-Phosphorus Bonds in Ni5cu3/Cop for Efficient Water Splitting

Abstract

Designing and fabricating heterostructure electrocatalysts composed of alloys and transition metal compounds might be a promising strategy for high-efficiency electrocatalysis. Herein, by anchoring a layer of Ni5Cu3 alloy on CoP nanorods with the help of an electrodeposition strategy, an efficient alloy-compound heterointerface catalyst for water splitting, Ni5Cu3/CoP, was designed and fabricated successfully. As shown from the experiments, the alloying effect of the Ni5Cu3/CoP catalyst induced a super-strong interfacial coupling due to the significant electron outflow from the Ni5Cu3 alloy, and it was the synergy of this alloying effect and super-strong interfacial coupling that resulted in the significant activation of cobalt-phosphorus bonds on the catalyst surface to generate rich active sites, which remarkably activated the intrinsic activity of Ni5Cu3/CoP. Therefore, in alkaline condition, Ni5Cu3/CoP exhibited low HER overpotential of 66 mV and OER overpotential of 190 mV at 10 mA·cm-2, respectively, as well as only needed a small cell voltage of 1.51 V to achieve 10 mA·cm-2 for overall water splitting. Density functional theory results revealed that alloy-induced strong interfacial coupling considerably optimized the adsorption of OER and HER intermediates, improving the catalytic activity. These findings provided a valuable insight for the subsequent development of heterogeneous catalysts containing alloy components.

Keywords: Strong interfacial coupling, alloying effect, Activation of Co-P Bonds, Ni5Cu3/CoP, Water Splitting